Digital broadcasting system and method of processing data

ABSTRACT

A digital broadcasting system and a method of processing data are disclosed. Herein, additional encoding is performed on mobile service data, which are then transmitted, thereby providing robustness in the processed mobile service data, so that the mobile service data can respond more strongly against fast and frequent channel changes. In a transmitting system including a service multiplexer and a transmitter located in a remote site, a method of processing data of the transmitting system includes comparing an output data rate of the service multiplexer and a transmission data rate of the transmitter, when a difference occurs between the two data rates, adjusting a burst size, wherein the burst transmits mobile service data, and encoding the mobile service data, and referring to the burst size so as to multiplex main service data and the encoded mobile service data in a burst structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. §119(a), this application claims the benefit ofearlier filing date and right of priority to Korean Patent ApplicationNo. 10-2007-0026905, filed on Mar. 20, 2007, and pursuant to 35 U.S.C.§119(e), also claims the benefit of U.S. Provisional Application No.60/900,257, filed on Feb. 7, 2007, the contents of which are all herebyincorporated by reference herein in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a digital broadcasting system and amethod of processing data.

2. Discussion of the Related Art

The Vestigial Sideband (VSB) transmission mode, which is adopted as thestandard for digital broadcasting in North America and the Republic ofKorea, is a system using a single carrier method. Therefore, thereceiving performance of the receiving system may be deteriorated in apoor channel environment. Particularly, since resistance to changes inchannels and noise is more highly required when using portable and/ormobile broadcast receivers, the receiving performance may be even moredeteriorated when transmitting mobile service data by the VSBtransmission mode.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a digital broadcastingsystem and a method of processing data that substantially obviate one ormore problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a digital broadcastingsystem and a method of processing data that are highly resistant tochannel changes and noise.

Another object of the present invention is to provide a digitalbroadcasting system and a method of processing data that can enhance thereceiving performance by performing additional encoding on mobileservice data and by transmitting the processed data to the receivingsystem.

A further object of the present invention is to provide a digitalbroadcasting system and a method of processing data that can match datarates of a service multiplexer and a transmitter by adjusting the datarate of the transmitter, when a difference occurs between the data rateof the service multiplexer and the data rate of the transmitter.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, in atransmitting system including a service multiplexer and a transmitterlocated in a remote site, a method of processing data of thetransmitting system includes comparing an output data rate of theservice multiplexer and a transmission data rate of the transmitter,when a difference occurs between the two data rates, adjusting a burstsize, wherein the burst transmits mobile service data, and encoding themobile service data, and referring to the burst size so as to multiplexmain service data and the encoded mobile service data in a burststructure.

In another aspect of the present invention, in a transmitting systemincluding a service multiplexer and a transmitter located in a remotesite, a method of processing data of the transmitting system includescomparing an output data rate of the service multiplexer and atransmission data rate of the transmitter, when a difference occursbetween the two data rates, adjusting a burst period, wherein the bursttransmits mobile service data, and encoding the mobile service data, andreferring to the burst period so as to multiplex main service data andthe encoded mobile service data in a burst structure.

In another aspect of the present invention, in a transmitting systemincluding a service multiplexer and a transmitter located in a remotesite, a method of processing data of the transmitting system includescomparing an output data rate of the service multiplexer and atransmission data rate of the transmitter, when a difference occursbetween the two data rates, inserting or removing transmission null datain or from mobile service data, so as to adjusting the data rate,encoding the processed mobile service data, the mobile service datahaving the transmission null data inserted therein or removed therefrom,and multiplexing main service data and the encoded mobile service datain a burst structure.

In another aspect of the present invention, a service multiplexer of atransmitting system includes a mobile service multiplexer, a null packetgenerator, and a transport packet multiplexer. The mobile servicemultiplexer multiplexes at least one mobile service data type, PSI/PSIPtables for mobile service, and space-filler null data at a predeterminedfirst data rate and outputs the multiplexed data. The null packetgenerator generates space-filler null data, so as to match an outputdata rate of the mobile service data multiplexer at the first data rate,and outputs the generated space-filler null data to the mobile servicemultiplexer. The transport packet multiplexer multiplexes at least onemain service data type and PSI/PSIP tables for main service at apredetermined second data rate, and multiplexes the data outputted fromthe mobile service multiplexer at a predetermined third data rate,thereby outputting the multiplexed data to a transmitter located at aremote site.

In a further aspect of the present invention, a transmitter of atransmitting system includes a demultiplexer, a buffer, a pre-processor,a buffer controller, and a packet multiplexer. The demultiplexerreceives data transmitted from a service multiplexer at a predetermineddata rate, thereby identifying mobile service data, main service data,and space-filler null data. The buffer temporarily stores the mobileservice identified by the demultiplexer and outputs the temporarilystored data. The pre-processor encodes the data outputted from thebuffer. The buffer controller monitors input and output data rates ofthe buffer, thereby adjusting transmission parameters associated with aburst for transmitting mobile service data, when a difference betweenthe two data rates occurs. And, the packet multiplexer refers to thetransmission parameters, thereby multiplexing the mobile service datapacket and a main service data packet including main service data in aburst structure.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiments of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 illustrates a block diagram showing a general structure of atransmitting system according to an embodiment of the present invention;

FIG. 2 illustrates a block diagram showing an example of a servicemultiplexer of FIG. 1;

FIG. 3 illustrates a block diagram showing an example of a transmitterof FIG. 1;

FIG. 4 illustrates a block diagram showing an example of a pre-processorof FIG. 3;

FIG. 5 and FIG. 6 illustrate data configuration before and after a datadeinterleaver in a transmitting system according to the presentinvention;

FIG. 7 illustrates burst and data group structures according to anembodiment of the present invention;

FIG. 8 illustrates a data structure showing an example of adjusting datarate according to an embodiment of the present invention;

FIG. 9 illustrates a flow chart showing an example of adjusting datarate according to an embodiment of the present invention;

FIG. 10 illustrates a data structure showing an example of adjustingdata rate according to another embodiment of the present invention;

FIG. 11 illustrates a flow chart showing an example of adjusting datarate according to another embodiment of the present invention;

FIG. 12 illustrates a flow chart showing an example of adjusting datarate according to yet another embodiment of the present invention; and

FIG. 13 illustrates a block diagram showing a structure of a receivingsystem according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts. In addition,although the terms used in the present invention are selected fromgenerally known and used terms, some of the terms mentioned in thedescription of the present invention have been selected by the applicantat his or her discretion, the detailed meanings of which are describedin relevant parts of the description herein. Furthermore, it is requiredthat the present invention is understood, not simply by the actual termsused but by the meaning of each term lying within.

Among the terms used in the description of the present invention, mainservice data correspond to data that can be received by a fixedreceiving system and may include audio/video (A/V) data. Morespecifically, the main service data may include A/V data of highdefinition (HD) or standard definition (SD) levels and may also includediverse data types required for data broadcasting. Also, the known datacorrespond to data pre-known in accordance with a pre-arranged agreementbetween the receiving system and the transmitting system. Additionally,in the present invention, mobile service data may include at least oneof mobile service data, pedestrian service data, and handheld servicedata, and are collectively referred to as mobile service data forsimplicity. Herein, the mobile service data not only correspond tomobile/pedestrian/handheld service data (M/P/H service data) but mayalso include any type of service data with mobile or portablecharacteristics. Therefore, the mobile service data according to thepresent invention are not limited only to the M/P/H service data.

The above-described mobile service data may correspond to data havinginformation, such as program execution files, stock information, and soon, and may also correspond to A/V data. Most particularly, the mobileservice data may correspond to A/V data having lower resolution andlower data rate as compared to the main service data. For example, if anA/V codec that is used for a conventional main service corresponds to aMPEG-2 codec, a MPEG-4 advanced video coding (AVC) or scalable videocoding (SVC) having better image compression efficiency may be used asthe A/V codec for the mobile service. Furthermore, any type of data maybe transmitted as the mobile service data. For example, transportprotocol expert group (TPEG) data for broadcasting real-timetransportation information may be serviced as the main service data.

Also, a data service using the mobile service data may include weatherforecast services, traffic information services, stock informationservices, viewer participation quiz programs, real-time polls andsurveys, interactive education broadcast programs, gaming services,services providing information on synopsis, character, background music,and filming sites of soap operas or series, services providinginformation on past match scores and player profiles and achievements,and services providing information on product information and programsclassified by service, medium, time, and theme enabling purchase ordersto be processed. Herein, the present invention is not limited only tothe services mentioned above. In the present invention, the transmittingsystem provides backward compatibility in the main service data so as tobe received by the conventional receiving system. Herein, the mainservice data and the mobile service data are multiplexed to the samephysical channel and then transmitted.

Additionally, the transmitting system according to the present inventionperforms additional encoding on the mobile service data and inserts thedata already known by the receiving system and transmitting system(e.g., known data), thereby transmitting the processed data. Therefore,when using the transmitting system according to the present invention,the receiving system may receive the mobile service data during a mobilestate and may also receive the mobile service data with stabilitydespite various distortion and noise occurring within the channel.Furthermore, when a difference occurs between the data rate of theservice multiplexer within the transmitting system and the data rate ofthe transmitter, the transmitter may adjust its data rate. Particularly,when a difference occurs between the data rate of the mobile servicedata outputted from the service multiplexer and the data rate of thedata transmitted from the transmitter, the transmitter is capable ofadjusting (or controlling) the difference in data rates.

FIG. 1 illustrates a block diagram showing a general structure of atransmitting system according to an embodiment of the present invention.Herein, the transmitting includes a service multiplexer 100 and atransmitter 200. Herein, the service multiplexer 100 is located in thestudio of each broadcast station, and the transmitter 200 is located ina site placed at a predetermined distance from the studio. Thetransmitter 200 may be located in a plurality of different locations.Also, for example, the plurality of transmitters may share the samefrequency. And, in this case, the plurality of transmitters receives thesame signal. This corresponds to a data transmission using a singlefrequency network (SFN). Accordingly, in the receiving system, a channelequalizer may compensate signal distortion, which is caused by areflected wave, so as to recover the original signal. In anotherexample, the plurality of transmitters may have different frequencieswith respect to the same channel. This corresponds to a datatransmission using a multiple frequency network (MFN).

A variety of methods may be used for data communication among each ofthe transmitters, which are located in remote positions, and the servicemultiplexer. For example, an interface standard such as a synchronousserial interface for transport of MPEG-2 data (SMPTE-310M). In theSMPTE-310M interface standard, a constant data rate is decided as anoutput data rate of the service multiplexer. For example, in case of the8 VSB mode, the output data rate is 19.39 Mbps, and, in case of the 16VSB mode, the output data rate is 38.78 Mbps. Furthermore, in theconventional 8 VSB mode transmitting system, a transport stream (TS)packet having a data rate of approximately 19.39 Mbps may be transmittedthrough a single physical channel. Also, in the transmitting systemaccording to the present invention provided with backward compatibilitywith the conventional transmitting system, additional error correctionencoding is performed on the mobile service data. Thereafter, theadditionally encoded mobile service data are multiplexed with the mainservice data to a TS packet form, which is then transmitted. At thispoint, the data rate of the multiplexed TS packet is approximately 19.39Mbps.

At this point, the service multiplexer 100 receives at least one type ofmain service data and program specific information/program and systeminformation protocol (PSI/PSIP) table data for each main service so asto encapsulate the received data to a TS packet, respectively. Also, theservice multiplexer 100 receives at least one type of mobile servicedata and PSI/PSIP table data for each mobile service and encapsulatesthe received data to transport stream (TS) packets. Subsequently, the TSpackets are multiplexed according to a predetermined multiplexing ruleand outputs the multiplexed packets to the transmitter 200.

FIG. 2 illustrates a block diagram showing an example of the servicemultiplexer 100. The service multiplexer 100 includes a controller 110controlling the overall operations of the service multiplexer, a mainservice PSI/PSIP generator 120, a mobile service PSI/PSIP generator 130,a null packet generator 140, a mobile service multiplexer 150, and atransport multiplexer 160. The transport multiplexer 160 may include amain service multiplexer 161 and a transport stream (TS) packetmultiplexer 162. Referring to FIG. 2, at least one type of compressionencoded main service data and the PSI/PSIP table data generated from themain service PSI/PSIP generator 120 are inputted to the main servicemultiplexer 161 of the transport multiplexer 160. The main servicemultiplexer 161 encapsulates each of the inputted main service data andPSI/PSIP table data to MPEG-2 TS packet forms. Then, the MPEG-2 TSpackets are multiplexed and outputted to the TS packet multiplexer 162.Herein, the data packet being outputted from the main servicemultiplexer 161 will be referred to as a main service data packet forsimplicity.

Thereafter, at least one type of the compression encoded mobile servicedata and the PSI/PSIP table data generated from the mobile servicePSI/PSIP generator 130 are inputted to the mobile service multiplexer150. At this point, the PSI/PSIP tables for mobile service may includeat least one transmission parameter corresponding to each mobileservice. In this case, based upon the control of the mobile servicemultiplexer 150, the PSI/PSIP generator 130 generates the transmissionparameters. Then, the generated transmission parameters may be includedin the corresponding table within PSI/PSIP tables pre-arranged with thetransmitter 200, thereby outputted to the mobile service multiplexer150. The mobile service multiplexer 150 encapsulates each of theinputted mobile service data and PSI/PSIP table data to MPEG-2 TS packetforms. Then, the MPEG-2 TS packets are multiplexed and outputted to theTS packet multiplexer 162. Herein, the data packet being outputted fromthe mobile service multiplexer 150 will be referred to as a mobileservice data packet for simplicity.

At this point, the transmitter 200 requires identification informationin order to identify and process the main service data packet and themobile service data packet. Herein, the identification information mayuse values pre-decided in accordance with an agreement between thetransmitting system and the receiving system, or may be configured of aseparate set of data, or may modify a predetermined location valuewithin the corresponding data packet. Herein, any value that canidentify each data packet may be used as the identification information.Therefore, the present invention is not limited only to the examples setforth in the description of the present invention.

As an example of the present invention, a different packet identifier(PID) may be assigned (or allocated) to identify each of the mainservice data packet and the mobile service data packet. In anotherexample, by modifying a synchronization data byte within a header of themobile service data, the service data packet may be identified by usingthe synchronization data byte value of the corresponding service datapacket. For example, the synchronization byte of the main service datapacket directly outputs the value decided by the ISO/IEC13818-1 standard(i.e., 0x47) without any modification. The synchronization byte of themobile service data packet modifies and outputs the value, therebyidentifying the main service data packet and the mobile service datapacket. Conversely, the synchronization byte of the main service datapacket is modified and outputted, whereas the synchronization byte ofthe mobile service data packet is directly outputted without beingmodified, thereby enabling the main service data packet and the mobileservice data packet to be identified.

A plurality of methods may be applied in the method of modifying thesynchronization byte. For example, each bit of the synchronization bytemay be inversed, in other words, bitwise inversion may be performed, oronly a portion of the synchronization byte may be inversed. As describedabove, any value that can be used to identify the main service datapacket and the mobile service data packet may be used herein as theidentification information. Therefore, the scope of the presentinvention is not limited only to the example set forth in thedescription of the present invention.

Meanwhile, a transport multiplexer used in the conventional digitalbroadcasting system may be used as the transport multiplexer 160according to the present invention. More specifically, in order tomultiplex the mobile service data and the main service data and totransmit the multiplexed data, the data rate of the main service islimited to a data rate of (19.39-K) Mbps. Then, K Mbps, whichcorresponds to the remaining data rate, is assigned as the data rate ofthe mobile service. Thus, the transport multiplexer which is alreadybeing used may be used as it is without any modification. Herein, thetransport multiplexer 160 multiplexes the main service data packet beingoutputted from the main service multiplexer 161 and the mobile servicedata packet being outputted from the mobile service multiplexer 150.Thereafter, the transport multiplexer 160 transmits the multiplexed datapackets to the transmitter 200.

However, in some cases, the output data rate of the mobile servicemultiplexer 150 may not be equal to K Mbps. In this case, the mobileservice multiplexer 150 multiplexes and outputs null data packetsgenerated from the null packet generator 140, so that the output datarate can be adjusted to K Mbps. More specifically, the null packetgenerator 140 generates null data packets in order to set the outputdata rate of the mobile service multiplexer 150 to a constant data rate.Then, the null packet generator 140 outputs the multiplexed null datapackets to the mobile service multiplexer 150. Herein, the null datapackets generated from the null packet generator 140 will be referred toas space-filler null data packets (or null data packets for filler) forsimplicity.

For example, when the service multiplexer 100 assigns K Mbps of the19.39 Mbps to the mobile service data, and when the remaining (19.39-K)Mbps is, therefore, assigned to the main service data, the data rate ofthe mobile service data that are multiplexed by the service multiplexer100 actually becomes lower than K Mbps. This is because thepre-processor of the transmitter 200 performs additional encoding on themobile service data, thereby increasing the amount of data. Eventually,the data rate of the mobile service data, which may be transmitted fromthe service multiplexer 100, becomes smaller than K Mbps.

For example, since the pre-processor of the transmitter 200 performs anencoding process on the mobile service data at a coding rate of at least1/2, the amount of the data outputted from the pre-processor isincreased to more than twice the amount of the data initially inputtedto the pre-processor. Accordingly, the sum of the data rate of the mainservice data and the data rate of the mobile service data, both beingmultiplexed by the service multiplexer 100, becomes smaller than orequal to 19.39 Mbps. Therefore, in order to match the data rate of thedata that are finally outputted from the service multiplexer 100 to aconstant data rate (e.g., 19.39 Mbps), an amount of null data packetscorresponding to the amount of lacking data rate is generated from thenull packet generator 140 and outputted to the mobile servicemultiplexer 150.

Accordingly, the mobile service multiplexer 150 encapsulates each of themobile service data and the PSI/PSIP table data that are being inputtedto a MPEG-2 TS packet form. Then, the above-described TS packets aremultiplexed with the space-filler null data packets and, then, outputtedto the TS packet multiplexer 162. Thereafter, the transport multiplexer160 multiplexes the main service data packet being outputted from themain service multiplexer 161 and the mobile service data packet beingoutputted from the mobile service multiplexer 150 and transmits themultiplexed data packets to the transmitter 200 at a data rate of 19.39Mbps.

According to an embodiment of the present invention, the mobile servicemultiplexer 150 receives the space-filler null data packets. However,this is merely exemplary and does not limit the scope of the presentinvention. In other words, according to another embodiment of thepresent invention, the TS packet multiplexer 162 may receive thespace-filler null data packets, so as to match the data rate of thefinal output data to a constant rate. Herein, the output path andmultiplexing rule of the space-filler null data packets is controlled bythe controller 110. The controller 110 controls the multiplexingprocesses performed by the mobile service multiplexer 150, and the mainservice multiplexer 161 and TS packet multiplexer 162 of the transportmultiplexer 160, and also controls the space-filler null data packetgeneration of the null packet generator 140. At this point, thetransmitter 200 discards the space-filler null data packets transmittedfrom the service multiplexer 100 instead of transmitting thespace-filler null data packets.

Further, in order to allow the transmitter 200 to discard thespace-filler null data packets transmitted from the service multiplexer100 instead of transmitting them, identification information foridentifying the space-filler null data packets is required. Herein, theidentification information may use values pre-decided in accordance withan agreement between the transmitting system and the receiving system.For example, the value of the synchronization byte within the header ofthe null data packet may be modified so as to be used as theidentification information. Alternatively, a transport_error_indicatorflag may also be used as the identification information. Herein, anyinformation that can identify the space-filler null data packets may beused as the identification information. Therefore, the present inventionwill not be limited only to the example set forth in the description ofthe present invention.

In the description of the present invention, an example of using thetransport_error_indicator flag included in the header of thespace-filler null data packets as the identification information will begiven to describe an embodiment of the present invention. In this case,the transport_error_indicator flag of the space-filler null data packetis set to ‘1’, and the transport_error_indicator flag of the remainingdata packets are reset to ‘0’, so as to identify the space-filler nulldata packet. More specifically, when the null packet generator 140generates the space-filler null data packets, and if thetransport_error_indicator flag from the header field of thecorresponding space-filler null data packet is set to ‘1’ and thentransmitted, the space-filler null data packet may be identified and,therefore, be discarded.

FIG. 3 illustrates a block diagram showing the structure of thetransmitter 200 according to an embodiment of the present invention.Referring to FIG. 3, the transmitter 200 includes a demultiplexer 211, aPSI/PSIP decoder 212, a main data buffer 213, a packet jitter mitigator214, a mobile data buffer 215, a pre-processor 216, a buffer controller217, a signaling information provider 218, a packet multiplexer 219, apost-processor 220, a synchronization (or sync) multiplexer 230, and atransmission unit 240. Herein, the data packet transmitted from theservice multiplexer 100 is inputted to the demultiplexer 211 and thePSI/PSIP decoder 212. Based upon the control of the PSI/PSIP decoder212, the demultiplexer 211 determines (or identifies) whether thereceived data packet corresponds to a space-filler null data packet, amain service data packet, or a mobile service data packet. Thespace-filler null data packet identified by the demultiplexer 211 isdiscarded instead of being transmitted. On the other hand, the mainservice data packet identified by the demultiplexer 211 passes throughthe main data buffer 213 so as to be provided to the packet jittermitigator 214. And, the mobile service data packet identified by thedemultiplexer 211 passes through the mobile data buffer 215 so as to beprovided to the pre-processor 216.

At this point, a variety of methods may be used by the demultiplexer 211for identifying the space-filler null data packet, the main service datapacket, and the mobile service data packet. For example, thedemultiplexer 211 may identify the main service data and the mobileservice data based upon the PID value corresponding to the inputted datapacket. And, the demultiplexer 211 may identify the space-filler nulldata packet based upon the value of the transport_error_indicator flagfield. Among the data being transmitted from the service multiplexer100, the PSI/PSIP decoder 212 receives PSI/PSIP tables for main serviceand PSI/PSIP tables for mobile service so as to respectively recognizethe configurations of main service programs and mobile service programs.

Furthermore, the PSI/PSIP decoder 212 may refer to the PID andtransport_error_indicator flag field of the data packet that iscurrently being inputted, thereby generating a control signal, which iscapable of determining (or identifying) the inputted data packet as themain service data packet, the mobile service data packet, or thespace-filler null data packet. Thereafter, the PSI/PSIP decoder 212outputs the generated control signal to the demultiplexer 211.Accordingly, the demultiplexer 211 identifies the inputted data packetbased upon the received control signal, thereby discarding theidentified data packet or outputting the identified data packet to thecorresponding block. At this point, the PSI/PSIP tables for mobileservice may include at least one transmission parameter for each mobileservice. In this case, the PSI/PSIP decoder 212 parses the correspondingtransmission parameter and outputs the parsed transmission parameter tothe signaling information provider 218. Based upon the control of thebuffer controller 217, the signaling information provider 218 providessignaling information including the transmission parameter to blocksassociated with the transmitter 200 (e.g., the pre-processor, the packetmultiplexer, etc.) so that the corresponding blocks can use therespective transmission parameters.

For example, the transmission may include data group information,information on a region within a data group, RS frame information, superframe information, burst information, turbo code information, RS codeinformation, and so on. Additionally, the burst information may includeburst size information and burst period information. The burst periodrefers to a cycle period during which a burst transmitting the samemobile service type is repeated. And, the burst size indicates thenumber of data groups included in a burst. The data group may include aplurality of mobile service data packets. Herein, a plurality of suchdata groups is gathered (or grouped) to form a burst. The burst sectionrepresents a beginning (or starting) point of a current burst up to abeginning point of the next burst.

The burst section may be divided into a section including a data group(i.e., a burst-on section) and a section not including any data group(i.e., a burst-off section). A burst section is configured of aplurality of fields, wherein one field includes one data group. Theinformation included in the transmission parameter are merely examplespresented to facilitate the understanding of the present invention. And,the addition or deleting of the information included in the transmissionparameter may be easily modified by anyone skilled in the art.Therefore, the present invention will not be limited only to theexamples set forth herein.

At this point, the transmission parameter provided by the signalinginformation provider 218 may be varied based upon the control of thebuffer controller 217. For example, the burst size and the burst periodmay be varied. Furthermore, the signaling information outputted from thesignaling information provider 218 includes the transmission parameter.The pre-processor 216 performs additional encoding on the mobile servicedata, so that the mobile service data can respond more effectively tonoise and channel environment that undergoes frequent changes.Thereafter, the pre-processor 216 outputs the additionally encodedmobile service data to the packet multiplexer 219.

FIG. 4 illustrates a block diagram of the pre-processor 216 according toan embodiment of the present invention. Herein, the pre-processor 216includes a data randomizer 401, a RS frame encoder 402, a blockprocessor 403, a group formatter 404, a data deinterleaver 405, and apacket formatter 406. The pre-processor 216 according to the embodimentof the present invention refers to the transmission parameter providedby the signaling information provider 218, thereby performing additionalencoding on the mobile service data outputted from the mobile databuffer 215. More specifically, the data randomizer 401 receives mobileservice data and randomizes the received mobile service data, therebyoutputting the processed data to the RS frame encoder 402. At thispoint, by having the data randomizer 401 randomize the mobile servicedata, a later randomizing process on the mobile service data performedby the data randomizer 221 of the post-processor 220 may be omitted.

The RS frame encoder 402 groups a plurality of the received mobileservice data packets that have been randomized. Then, the RS frameencoder 402 performs at least one of an error correction encodingprocess and an error detection encoding process on the receivedrandomized mobile service data. Furthermore, the RS frame encoder 402may also group a plurality of RS frames so as to configure a superframe, thereby performing interleaving (or permutation) processes insuper frame units. Thus, by providing robustness on the mobile servicedata, the corresponding data may be able to respond to the severelyvulnerable and frequently changing frequency environment.

More specifically, when the RS frame encoder 402 performs rowpermutation based upon a predetermined rule for permuting each row ofthe super frame, the row positions within the super frame after the rowpermutation process may differ from the row positions within the superframe prior to the row permutation (or interleaving) process. Herein, byperforming the row permutation (or interleaving) process in super frameunits, even though the section having a plurality of errors occurringtherein becomes very long, and even though the number of errors includedin the RS frame that is to be decoded exceeds the extent of being ableto be corrected, the errors become dispersed within the entire superframe. Thus, the decoding ability is even more enhanced as compared to asingle RS frame.

In the RS frame encoder 402 according to the embodiment of the presentinvention, RS encoding is applied as the error correction encodingprocess, and cyclic redundancy check (CRC) encoding is applied as theerror detection encoding process. When performing RS encoding, paritydata that are to be used for error correction are generated. And, whenperforming CRC encoding, CRC data that are to be used for errordetection are generated. Also, according to the embodiment of thepresent invention, the RS encoding uses the forward error correction(FEC) structure. The FEC corresponds to a technique for compensatingerrors that occur during the transmission process. The CRC datagenerated by CRC encoding may be used for indicating whether or not themobile service data have been damaged by the errors while beingtransmitted through the channel. In the present invention, a variety oferror detection coding methods other than the CRC encoding method may beused, or the error correction coding method may be used to enhance theoverall error correction ability (or performance) of the receivingsystem.

Herein, the RS frame encoder 402 refers to the pre-set transmissionparameter and/or refers to the transmission parameter provided from thesignaling information provider 218, thereby being able to performprocesses including RS frame configuration, RS encoding, CRC encoding,super frame configuration, and row permutation (or interleaving) insuper frame units. As described above, the mobile service data encodedby the RS frame encoder 402 are inputted to the block processor 403. Theblock processor 403 then encodes the inputted mobile service data at acoding rate of G/H (wherein, G is smaller than H (i.e., G<H)) and thenoutputted to the group formatter 404.

More specifically, the block processor 403 divides the mobile servicedata being inputted in byte units into bit units. Then, the G number ofbits is encoded to H number of bits. Thereafter, the encoded bits areconverted back to byte units and then outputted. For example, if 1 bitof the input data is coded to 2 bits and outputted, then C is equal to 1and H is equal to 2 (i.e., G=1 and H=2). Alternatively, if 1 bit of theinput data is coded to 4 bits and outputted, then G is equal to 1 and His equal to 4 (i.e., G=1 and H=4). Hereinafter, the former coding ratewill be referred to as a coding rate of 1/2 (1/2-rate coding), and thelatter coding rate will be referred to as a coding rate of 1/4 (1/4-ratecoding), for simplicity.

Herein, when using the 1/4 coding rate, the coding efficiency is greaterthan when using the 1/2 coding rate, and may, therefore, provide greaterand enhanced error correction ability. For such reason, when it isassumed that the data encoded at a 1/4 coding rate in the groupformatter 404, which is located near the end portion of the system, areallocated to a region in which the receiving performance may bedeteriorated, and that the data encoded at a 1/2 coding rate areallocated to a region having excellent receiving performance, thedifference in performance may be reduced.

At this point, the block processor 403 may also receive signalinginformation including the transmission parameters. Herein, the signalinginformation is also encoded at the coding rate of 1/2 or the coding rateof 1/4, which is similarly processed as in the step for encoding themobile service data. Afterwards, the signaling information is consideredand treated identically as the mobile service data. Meanwhile, the groupformatter 404 inserts mobile service data that are outputted from theblock processor 403 in corresponding regions within a data group, whichis configured in accordance with a pre-defined rule. Also, with respectto the data deinterleaving process, each place holder or known data arealso inserted in corresponding regions within the data group. At thispoint, the data group may be divided into at least one hierarchicalregion. Herein, the type of mobile service data being inserted to eachregion may vary depending upon the characteristics of each hierarchicalregion. For example, each region may be divided based upon the receivingperformance within the data group.

In an example given in the present invention, a data group is dividedinto A, B, and C regions in a data configuration prior to datadeinterleaving. At this point, the group formatter 404 allocates themobile service data, which are inputted after being RS encoded and blockencoded, to each of the corresponding regions by referring to thetransmission parameter.

FIG. 5 illustrates an alignment of data after being data interleaved andidentified, and FIG. 6 illustrates an alignment of data before beingdata interleaved and identified. More specifically, a data structureidentical to that shown in FIG. 5 is transmitted to a receiving system.Also, the data group configured to have the same structure as the datastructure shown in FIG. 5 is inputted to the data deinterleaver 405.

As described above, FIG. 5 illustrates a data structure prior to datadeinterleaving that is divided into 3 regions, such as region A, regionB, and region C. Also, in the present invention, each of the regions Ato C is further divided into a plurality of regions. Referring to FIG.5, region A is divided into 5 regions (A1 to A5), region B is dividedinto 2 regions (B1 and B2), and region C is divided into 3 regions (C1to C3). Herein, regions A to C are identified as regions having similarreceiving performances within the data group. Herein, the type of mobileservice data, which are inputted, may also vary depending upon thecharacteristic of each region.

In the example of the present invention, the data structure is dividedinto regions A to C based upon the level of interference of the mainservice data. Herein, the data group is divided into a plurality ofregions to be used for different purposes. More specifically, a regionof the main service data having no interference or a very lowinterference level may be considered to have a more resistant (orrobust) receiving performance as compared to regions having higherinterference levels. Additionally, when using a system inserting andtransmitting known data in the data group, and when consecutively longknown data are to be periodically inserted in the mobile service data,the known data having a predetermined length may be periodicallyinserted in the region having no interference from the main service data(e.g., region A). However, due to interference from the main servicedata, it is difficult to periodically insert known data and also toinsert consecutively long known data to a region having interferencefrom the main service data (e.g., region B and region C).

Hereinafter, examples of allocating data to region A (A1 to A5), regionB (B1 and B2), and region C (C1 to C3) will now be described in detailwith reference to FIG. 5. The data group size, the number ofhierarchically divided regions within the data group and the size ofeach region, and the number of mobile service data bytes that can beinserted in each hierarchically divided region of FIG. 5 are merelyexamples given to facilitate the understanding of the present invention.Herein, the group formatter 404 creates a data group including places inwhich field synchronization data bytes are to be inserted, so as tocreate the data group that will hereinafter be described in detail.

More specifically, region A includes A2 to A5 regions within the datagroup in which a long known data sequence may be periodically inserted,and in which includes regions wherein the main service data are notmixed. Also, region A includes an A1 region located between a fieldsynchronization region and the region in which the first known datasequence is to be inserted. The field synchronization region has thelength of one segment (i.e., 832 symbols) existing in an ATSC system.

For example, referring to FIG. 5, 2428 bytes of the mobile service datamay be inserted in the region A1, 2580 bytes may be inserted in theregion A2, 2772 bytes may be inserted in the region A3, 2472 bytes maybe inserted in the region A4, and 2772 bytes may be inserted in theregion A5. Herein, trellis initialization data or known data, MPEGheader, and RS parity are not included in the mobile service data. Asdescribed above, when region A includes a known data sequence at bothends, the receiving system uses channel information that can obtainknown data or field synchronization data, so as to perform equalization,thereby providing enforced equalization performance.

Also, region B includes a B1 region located within 8 segments at thebeginning of a field synchronization region within the data group(chronologically placed before region A1), and a B2 region locatedwithin 8 segments behind the very last known data sequence which isinserted in the data group. For example, 930 bytes of the mobile servicedata may be inserted in the region B1, and 1350 bytes may be inserted inthe region B2. Similarly, trellis initialization data or known data,MPEG header, and RS parity are not included in the mobile service data.In case of region B, the receiving system may perform equalization byusing channel information obtained from the field synchronizationregion. Alternatively, the receiving system may also performequalization by using channel information that may be obtained from thelast known data sequence, thereby enabling the system to respond to thechannel changes.

Region C includes a C1 region located within 30 segments including andpreceding the 9^(th) segment of the field synchronization region(chronologically located before region A), a C2 region located within 12segments including and following the 9^(th) segment of the very lastknown data sequence within the data group (chronologically located afterregion A), and a C3 region located in 32 segments after the region C2.For example, 1272 bytes of the mobile service data may be inserted inthe region C1, 1560 bytes may be inserted in the region C2, and 1312bytes may be inserted in the region C3. Similarly, trellisinitialization data or known data, MPEG header, and RS parity are notincluded in the mobile service data. Herein, region C (e.g., region C1)is located chronologically earlier than (or before) region A.

Since region C (e.g., region C1) is located further apart from the fieldsynchronization region which corresponds to the closest known dataregion, the receiving system may use the channel information obtainedfrom the field synchronization data when performing channelequalization. Alternatively, the receiving system may also use the mostrecent channel information of a previous data group. Furthermore, inregion C (e.g., region C2 and region C3) located before region A, thereceiving system may use the channel information obtained from the lastknown data sequence to perform equalization. However, when the channelsare subject to fast and frequent changes, the equalization may not beperformed perfectly. Therefore, the equalization performance of region Cmay be deteriorated as compared to that of region B.

When it is assumed that the data group is allocated with a plurality ofhierarchically divided regions, as described above, the block processor403 may encode the mobile service data, which are to be inserted to eachregion based upon the turbo code information within the transmissionparameter, at a different coding rate.

In addition, apart from the encoded mobile service data outputted fromthe block processor 403, the group formatter 404 also inserts MPEGheader place holders, non-systematic RS parity place holders, mainservice data place holders, which are related to data deinterleaving ina later process. Herein, the main service data place holders areinserted because a region wherein the mobile service data bytes and themain service data bytes are alternately mixed with one another, basedupon the input of the data deinterleaver, exists. For example, basedupon the data outputted after the data-deinterleaving process, the placeholder for the MPEG header may be allocated at the very beginning ofeach packet.

Furthermore, the group formatter 404 either inserts known data generatedin accordance with a pre-determined method or inserts known data placeholders for inserting the known data in a later process. Additionally,place holders for initializing the trellis encoding module 226 of thepost-processor 220 are also inserted in the corresponding regions. Forexample, the initialization data place holders may be inserted in thebeginning of the known data sequence. Herein, the size of the mobileservice data that can be inserted in a data group may vary in accordancewith the sizes of the trellis initialization data or known data (orknown data place holders) MPEG header place holders, and RS parity placeholders.

The data outputted from the group formatter 404 are inputted to the datadeinterleaver 405. And, the data deinterleaver 405 deinterleaves data byperforming an inverse process of the data interleaver on the data andplace holders within the data group, which are then outputted to thepacket formatter 406. The packet formatter 406 removes the main servicedata place holders and the RS parity place holders that were allocatedfor the deinterleaving process from the deinterleaved data that arebeing inputted. Then, the packet formatter 406 groups the remainingportion and replaces the 4-byte MPEG header place holder with an MPEGheader.

Also, when the group formatter 404 inserts known data place holders, thepacket formatter 406 may insert actual known data in the known dataplace holders, or may directly output the known data place holderswithout any modification in order to make replacement insertion in alater process. Thereafter, the packet formatter 406 identifies the datawithin the packet-formatted data group, as described above, as a188-byte unit mobile service data packet (i.e., MPEG TS packet), whichis then provided to the packet multiplexer 219.

The packet multiplexer 219 multiplexes the mobile service data packetand the main service data packet outputted from the packet formatter 406in 188-byte units based upon a pre-defined multiplexing method. Then,the packet multiplexer 219 outputs the multiplexed data packets to thedata randomizer 221 of the post-processor 220. Herein, the multiplexingmethod may vary in accordance with various variables of the systemdesign. One of the multiplexing methods of the packet multiplexer 219consists of providing a burst section along a time axis and, then,transmitting a plurality of data groups during a burst section andtransmitting only the main service data during a non-burst section. Atthis point, main service data may also be transmitted in the burstsection. Furthermore, the packet multiplexer 219 can determine thenumber of data groups included in a single burst, the cycle period of asingle burst based upon the transmission parameters (e.g., informationof burst size or burst period) provided by the signaling informationprovider 218.

In this case, mobile service data and main service data co-exist in aburst section, and only the main service data exist in the non-burstsection. Therefore, the main service data section transmitting the mainservice data exist in both the burst section and the non-burst section.At this point, the number of main service data packets included in themain service data section within the burst section and the number ofmain service data packets included in the main service data sectionwithin the non-burst section may be equal to or different from oneanother. When the mobile service data are transmitted in burst units, asdescribed above, a receiving system that only receives the mobileservice data may turn on the power only during the burst section so asto receive the corresponding data. Also, in this case, the receivingsystem may turn off the power during non-burst sections, therebypreventing the main service data from being received. Thus, thereceiving system is capable of reducing excessive power consumption.

However, since a data group including mobile service data in-between thedata bytes of the main service data during the packet multiplexingprocess, the shifting of the chronological position (or place) of themain service data packet becomes relative. Also, a system object decoder(i.e., MPEG decoder) for processing the main service data of thereceiving system, receives and decodes only the main service data andrecognizes the mobile service data packet as a null data packet (orspace-filler null packet). Therefore, when the system object decoder ofthe receiving system receives a data group including mobile service dataand a main service data packet that is multiplexed with the data group,a packet jitter occurs.

At this point, since a multiple-level buffer for the video data existsin the system object decoder and the size of the buffer is relativelylarge, the packet jitter generated from the packet multiplexer 219 doesnot cause any serious problem in case of the video data. However, sincethe size of the buffer for the audio data is relatively small, thepacket jitter may cause some problem. More specifically, due to thepacket jitter, an overflow or underflow may occur in the buffer for themain service data of the digital broadcast receiving system (e.g., thebuffer for the audio data). Therefore, the packet jitter mitigator 214re-adjusts the relative position of the main service data packet so thatthe overflow or underflow does not occur in the system object decoder.

In the present invention, examples of repositioning places for the audiodata packets within the main service data in order to minimize theinfluence on the operations of the audio buffer will be described indetail. The packet jitter mitigator 214 repositions audio packets of themain service data section so that the audio data packets of the mainservice can be positioned as equally and uniformly as possible. Thestandard for repositioning the audio data packets in the main servicedata performed by the packet jitter mitigator 214 will now be described.Herein, it is assumed that the packet jitter mitigator 214 knows thesame multiplexing information as that of the packet multiplexer 219,which is placed further behind the packet jitter mitigator 214.

Firstly, if one audio data packet exists in the main service datasection (e.g., the main service data section positioned between two datagroups) within the burst section, the audio data packet is positioned atthe very beginning of the main service data section. Alternatively, iftwo audio data packets exist in the corresponding data section, oneaudio data packet is positioned at the very beginning and the otheraudio data packet is positioned at the very end of the main service datasection. Further, if more than three audio data packets exist, one audiodata packet is positioned at the very beginning of the main service datasection, another is positioned at the very end of the main service datasection, and the remaining audio data packets are positioned between thefirst and last audio data packets at equal intervals.

Secondly, during the main service data section before the beginning of aburst section, the audio data packet is placed at the very end of themain service data section. Thirdly, during a main service data sectionafter the end of burst section, the audio data packet is positioned atthe very beginning of the main service data section. And, finally, thedata packets other than audio data packets are positioned to vacantspaces (i.e., spaces that are not designated for the audio data packets)in accordance with the inputted order. Meanwhile, when the positions ofthe main service data packets are relatively re-adjusted, associatedprogram clock reference (PCR) values may also be modified accordingly.The PCR value corresponds to a time reference value for synchronizingthe time of the MPEG decoder. Herein, the PCR value is inserted in aspecific region of a TS packet and then transmitted. In the embodimentof the present invention, the packet jitter mitigator 214 may alsoperform the function of correcting (or modifying) the PCR value.

The data outputted from the packet jitter mitigator 214 are inputted tothe packet multiplexer 219. As described above, the packet multiplexer219 multiplexes the main service data packet outputted from the packetjitter mitigator 214 with the mobile service data packet outputted fromthe pre-processor 216 into a burst structure in accordance with apre-determined multiplexing rule. Then, the packet multiplexer 219outputs the multiplexed data packets to the data randomizer 221 of thepost-processor 220.

If the inputted data correspond to the main service data packet, thedata randomizer 221 performs the same randomizing process as that of theconventional randomizer. More specifically, the synchronization bytewithin the main service data packet is deleted. Then, the remaining 187data bytes are randomized by using a pseudo random byte generated fromthe data randomizer 221. Thereafter, the randomized data are outputtedto the RS encoder/non-systematic RS encoder 222. On the other hand, ifthe inputted data correspond to the mobile service data packet, the datarandomizer 221 deletes the synchronization byte from the 4-byte MPEGheader included in the mobile service data packet and, then, performsthe randomizing process only on the remaining 3 data bytes of the MPEGheader. Thereafter, the randomized data bytes are outputted to the RSencoder/non-systematic RS encoder 222.

Additionally, the randomizing process is not performed on the remainingportion of the mobile service data excluding the MPEG header. In otherwords, the remaining portion of the mobile service data packet isdirectly outputted to the RS encoder/non-systematic RS encoder 222without being randomized. This is because a randomizing process hasalready been performed on the mobile service data in the data randomizer401. Also, the data randomizer 221 may or may not perform a randomizingprocess on the known data (or known data place holders) and theinitialization data place holders included in the mobile service datapacket.

The RS encoder/non-systematic RS encoder 222 performs an RS encodingprocess on the data being randomized by the data randomizer 221 or onthe data bypassing the data randomizer 221, so as to add 20 bytes of RSparity data. Thereafter, the processed data are outputted to the datainterleaver 223. Herein, if the inputted data correspond to the mainservice data packet, the RS encoder/non-systematic RS encoder 222performs the same systematic RS encoding process as that of theconventional system, thereby adding the 20-byte RS parity data at theend of the 187-byte data. Alternatively, if the inputted data correspondto the mobile service data packet, the RS encoder/non-systematic RSencoder 222 performs a non-systematic RS encoding process. At thispoint, the 20-byte RS parity data obtained from the non-systematic RSencoding process are inserted in a pre-decided parity byte place withinthe mobile service data packet.

The data interleaver 223 corresponds to a byte unit convolutionalinterleaver. The output of the data interleaver 223 is inputted to theparity replacer 224 and to the non-systematic RS encoder 225. Meanwhile,a process of initializing a memory within the trellis encoding module226 is primarily required in order to decide the output data of thetrellis encoding module 226, which is located after the parity replacer224, as the known data pre-defined according to an agreement between thereceiving system and the transmitting system. More specifically, thememory of the trellis encoding module 226 should first be initializedbefore the received known data sequence is trellis-encoded. At thispoint, the beginning portion of the known data sequence that is receivedcorresponds to the initialization data place holder and not to theactual known data. Herein, the initialization data place holder has beenincluded in the data by the group formatter 404 in an earlier process.Therefore, the process of generating initialization data and replacingthe initialization data place holder of the corresponding memory withthe generated initialization data are required to be performedimmediately before the inputted known data sequence is trellis-encoded.

Additionally, a value of the trellis memory initialization data isdecided and generated based upon a memory status of the trellis encodingmodule 226. Further, due to the newly replaced initialization data, aprocess of newly calculating the RS parity and replacing the RS parity,which is outputted from the data interleaver 223, with the newlycalculated RS parity is required. Therefore, the non-systematic RSencoder 225 receives the mobile service data packet including theinitialization data place holders, which are to be replaced with theactual initialization data, from the data interleaver 223 and alsoreceives the initialization data from the trellis encoding module 226.

Among the inputted mobile service data packet, the initialization dataplace holders are replaced with the initialization data, and the RSparity data that are added to the mobile service data packet.Thereafter, a new non-systematic RS parity is calculated and thenoutputted to the parity replacer 224. Accordingly, the parity replacer224 selects the output of the data interleaver 223 as the data withinthe mobile service data packet, and the parity replacer 224 selects theoutput of the non-systematic RS encoder 225 as the RS parity data. Then,the selected data are outputted to the trellis encoding module 226.

Meanwhile, if the main service data packet is inputted or if the mobileservice data packet, which does not include any initialization dataplace holders that are to be replaced, is inputted, the parity replacer224 selects the data and RS parity that are outputted from the datainterleaver 223. Then, the parity replacer 224 directly outputs theselected data to the trellis encoding module 226 without anymodification. The trellis encoding module 226 converts the byte-unitdata to symbol units and performs a 12-way interleaving process so as totrellis-encode the received data. Thereafter, the processed data areoutputted to the synchronization multiplexer 230. The synchronizationmultiplexer 230 inserts a field synchronization signal and a segmentsynchronization signal to the data outputted from the trellis encodingmodule 226 and, then, outputs the processed data to the pilot inserter241 of the transmission unit 240. Herein, the data having a pilotinserted by the pilot inserter 241 are modulated by the modulator 242 inaccordance with a pre-decided modulating method (e.g., VSB method).Thereafter, the modulated data are transmitted to each receiving systemthrough the radio frequency (RF) up-converter 243.

Meanwhile, the mobile service multiplexer 150 and the transmitter 200should be connected with one another so as to closely communicate withone another. Although the mobile service multiplexer 150 decides thetransmission parameter that is to be used, when the transmitter 200transmits data, the transmission parameter decides the data rate of thedata transmitted from the transmitter 200. When the service multiplexer100 multiplexes the mobile service data and PSI/PSIP tables for mainservice with the main service data and PSI/PSIP tables for mobileservice in TS packet units, the average data rate of each service ismaintained at the same rate preset by the service multiplexer 100.

However, when the demultiplexer 211 of the transmitter 200 discards (orremoves) the space-filler null data packet, thereby identifying the datapacket as the main service data packet and the mobile service datapacket, the data rate of the mobile service data packet is constantlychanged. Therefore, in order to allow the data transmission to beprocessed from the transmitter 200 at a constant data rate, thedemultiplexed main service data packet is temporarily stored in the maindata buffer 213 and then provided to the packet jitter mitigator 214.Alternatively, the demultiplexed mobile service data packet istemporarily stored in the mobile data buffer 215 and then provided tothe preprocessor 216.

At this point, a large number of mobile service data packets exceedingthe size of the mobile data buffer 215 may temporarily seek to beaccumulated in the mobile data buffer 215. Such phenomenon occurs whenthe data rate of the mobile service data packet being inputted to themobile data buffer 215 is greater (or faster) than the data rate of themobile service data packet being outputted from the mobile data buffer215. This phenomenon is referred to as an overflow. Conversely, thenumber of mobile service data packets accumulated in the mobile databuffer 215 may be temporarily small (or insufficient). Therefore, allmobile service data packets within the mobile data buffer 215 may beoutputted before a new mobile service data packet is inputted to themobile data buffer 215. Such phenomenon occurs when the data rate of themobile service data packet being inputted to the mobile data buffer 215is smaller (or slower) than the data rate of the mobile service datapacket being outputted from the mobile data buffer 215. This phenomenonis referred to as an underflow.

However, when either an overflow or an underflow occurs in the mobiledata buffer 215, a problem may occur in the service transmissionprocessed through the transmitter 200. For example, when an overflowoccurs, a new set of data may overwrite the already-existing data withinthe mobile data buffer 215, even before the data existing in the mobiledata buffer 215 can be transmitted, thereby causing the previous (oralready-existing) data to be lost. On the other hand, when an underflowoccurs, the transmitter 200 may irregularly transmit large amounts ofnull data to the receiving system, thereby causing problems in datareception control and data decoding in the receiving system.

In another example, the data rate of the mobile service data beinginputted to the mobile service multiplexer 150 and the transmission datarate of the transmitter 200 may not accurately match. Such phenomenonmay occur when the mobile service multiplexer 150 multiplexes the mobileservice data without being able to accurately provide (or support) thedata rate for each transmission mode of the transmitter 200. At thispoint, the mobile service multiplexer 150 controls the PSI/PSIPgenerator 130 to generate transmission parameters so that the mobileservice data can be transmitted at a data rate most approximate to theoutput data rate corresponding to each transmission mode of thetransmitter 200. Thereafter, the mobile service multiplexer 150transmits the generated transmission parameters to the transmitter 200.However, the above-described problem, which may occur in the servicetransmission processed through the transmitter 200, may also occur inthe example given herein.

In order to resolve such problems, the transmitter 200 may temporarilycontrol the transmission parameters so as to compensate the data rate.According to the present invention, a method for compensating the datarate by controlling the transmission parameters may include a method ofcontrolling the burst period, a method of controlling the burst size,and so on. According to another embodiment of the present invention, thetransmitter 200 may temporarily add or remove additional null datapackets, thereby compensating the data rate. At this point, the datarate is adjusted in connection with the amount of data accumulated inthe mobile data buffer 215.

FIG. 7 illustrates exemplary operations of the packet multiplexer 219according to a detailed embodiment of the present invention. Herein,FIG. 7 illustrates an example of performing data transmission in burstunits based upon the transmission parameters. More specifically, FIG. 7illustrates an example of two different mobile service data types (e.g.,two mobile service programs) being multiplexed in burst units with mainservice data. Referring to FIG. 7, 118 mobile service data packetsgathered (or grouped) to configure a data group, and 18 data groups aregrouped to form a burst. In other words, 18 data groups are transmittedas a single burst.

According to an embodiment of the present invention, two burst sectionsfor the two types of mobile service each includes 18 data groups, eachburst being repeated at a cycle period of 60 fields. Herein, one burstsection is configured of 30 fields, wherein a burst-on section includes18 fields, and a burst-off section includes 12 fields. Morespecifically, one field within the burst-on section includes one datagroup. For example, when a data group is configured of 118 data packets,as shown in FIG. 7, a main service data packet may be transmitted to theremaining 194 data packet sections within the corresponding field. Eachfield consists of 312 data segments, wherein the data within the datagroup are allocated to 118 segments, and wherein the main service dataare allocated to 194 segments.

Alternatively, if the packet multiplexer 219 of FIG. 7 transmits asingle mobile service type, each burst section includes 18 data groups,and the repetition cycle period of each burst corresponds to 30 fields.At this point, the burst size of each mobile service or the transmissionparameters applied in the pre-processor 216 may be applied differentlyfor each service type. And, as described above, the mobile servicemultiplexer 150 may notify (or transmit) the transmission parameters tothe transmitter 200 in a PSI/PSIP format.

When the transmitting system transmits the mobile service data in aburst structure, as described above, the receiving system turns on thepower only during the corresponding burst section including the desiredservice, thereby receiving the corresponding service data. On the otherhand, the receiving system turns off the power during the remainingburst sections, thereby enabling the receiving system to reduceexcessive power consumption. Furthermore, even when the receiving systemturns on the power during the burst-on section, wherein a burst sectionincludes a data group, thereby receiving data, and even when the samereceiving system turns off the power during the burst-off section, so asto reduce power consumption, the data receiving performance is notaffected.

FIG. 8 illustrates a data structure showing an example of a method forcompensating data rate performed by the transmitter according to a firstembodiment of the present invention. Herein, FIG. 8 illustrates anexample wherein the data rate is compensated by adjusting the burstsize. More specifically, FIG. 8 illustrates an example of enlarging theburst size so that a larger number of mobile service data packets can beoutputted from the mobile data buffer 215 as compared to the averageoutput rate. This example may be applied when the data rate of themobile service data packet being inputted to the mobile data buffer 215is greater (or faster) than the data rate of the mobile service datapacket being outputted from the mobile data buffer 215.

According to the first embodiment of the present invention, first andsecond threshold values are predetermined. And, when the amount of dataaccumulated in the mobile data buffer 215 is larger than the firstthreshold value, it is determined that an overflow has occurred. On theother hand, when the amount of data accumulated in the mobile databuffer 215 is smaller than the second threshold value, it is determinedthat an underflow has occurred. However, if the amount of dataaccumulated in the mobile data buffer 215 is between the first andsecond threshold values, then the data rate is not required to becompensated. Accordingly, in this case, the burst size is not adjusted.Furthermore, when an overflow occurs, the burst size is enlarged so thata larger number of mobile service data packets can be outputted from themobile data buffer 215 than the average output rate. Conversely, when anunderflow occurs, the burst size is reduced so that a smaller number ofmobile service data packets can be outputted from the mobile data buffer215 than the average output rate.

At this point, according to the embodiment of the present invention, thebuffer controller 217 sets the first and second threshold values andadjusts the burst size. More specifically, the buffer controller 217monitors the mobile data buffer 215. Then, when an overflow or underflowoccurs, the buffer controller 217 adjusts the burst size among thetransmission parameters of the signaling information provider 218.Subsequently, the signaling information provider 218 transmits thetransmission parameters including the adjusted burst size information tothe corresponding block.

FIG. 9 illustrates a flow chart showing an example of a method forcompensating data rate performed by the transmitter according to thefirst embodiment of the present invention. Herein, FIG. 9 illustrates anexample wherein the data rate is compensated by adjusting the burstsize. More specifically, the mobile service data packet demultiplexed bythe demultiplexer 211 is temporarily stored in the mobile data buffer215 and then outputted (S501). At this point, the buffer controller 217determines whether the amount of data accumulated in the mobile databuffer 215 is larger than the first threshold value (S502).

When, the buffer controller 217 determines that the amount of dataaccumulated in the mobile data buffer 215 is larger than the firstthreshold value, the buffer controller 217 enlarges the burst size sothat a larger number of mobile service data packets can be outputtedfrom the mobile data buffer 215 than the average output rate (S503).More specifically, while monitoring the amount of data being accumulatedin the mobile data buffer 215, when the number of data packets beingaccumulated in the mobile data buffer 215 is larger than thepredetermined first threshold value, the buffer controller 217temporarily controls the corresponding transmission parameter so thatthe burst size can be enlarged. For example, when the current burst sizeis set to be equal to 18 data groups, and when an overflow occurs, thecorresponding transmission parameter of the signaling informationprovider 218 is controlled so that the next burst size can be enlargedto 19 data groups, as shown in FIG. 8. In this case, the burst period isnot altered. Therefore, the burst-on section within the correspondingburst section includes 19 fields, and the burst-off section includes 11fields. Thereafter, the adjusted transmission parameter is provided tothe pre-processor 216 and packet multiplexer 219 of the transmitter 200and simultaneously transmitted to the receiving system.

Meanwhile, the buffer controller 217 also determines whether the amountof data accumulated in the mobile data buffer 215 is smaller than thesecond threshold value (S505). When, the buffer controller 217determines that the amount of data accumulated in the mobile data buffer215 is smaller than the second threshold value, the buffer controller217 reduces the burst size so that a smaller number of mobile servicedata packets can be outputted from the mobile data buffer 215 than theaverage output rate (S506). Accordingly, the number of mobile servicedata packets accumulated in the mobile data buffer 215 may be increased.

More specifically, while monitoring the amount of data being accumulatedin the mobile data buffer 215, when the number of data packets beingaccumulated in the mobile data buffer 215 is smaller than thepredetermined second threshold value, the buffer controller 217temporarily controls the corresponding transmission parameter so thatthe burst size can be reduced. For example, when the current burst sizeis set to be equal to 18 data groups, and when an underflow occurs, thecorresponding transmission parameter of the signaling informationprovider 218 is controlled so that the next burst size can be reduced to17 data groups. In this case, the burst period is not altered.Therefore, the burst-on section within the corresponding burst sectionincludes 17 fields, and the burst-off section includes 13 fields.

Thereafter, the adjusted transmission parameter is provided to thepre-processor 216 and packet multiplexer 219 of the transmitter 200 andsimultaneously transmitted to the receiving system. The pre-processor216 then performs pre-processes on the mobile service data packets basedupon the corresponding transmission parameter, and the packetmultiplexer 219 refers to the adjusted burst size so as to multiplex theoutput of the packet jitter mitigator 214 and the output of thepre-processor 216, thereby transmitting the multiplexed data in a burststructure (S504).

FIG. 10 illustrates a data structure showing an example of a method forcompensating data rate performed by the transmitter according to asecond embodiment of the present invention. Herein, FIG. 10 illustratesan example wherein the data rate is compensated by adjusting the burstperiod. More specifically, FIG. 10 illustrates an example of reducingthe burst period so that a larger number of mobile service data packetscan be outputted from the mobile data buffer 215 as compared to theaverage output rate. This example may be applied when the data rate ofthe mobile service data packet being inputted to the mobile data buffer215 is greater (or faster) than the data rate of the mobile service datapacket being outputted from the mobile data buffer 215.

According to the second embodiment of the present invention, first andsecond threshold values are also predetermined. And, when the amount ofdata accumulated in the mobile data buffer 215 is larger than the firstthreshold value, it is determined that an overflow has occurred. On theother hand, when the amount of data accumulated in the mobile databuffer 215 is smaller than the second threshold value, it is determinedthat an underflow has occurred. However, if the amount of dataaccumulated in the mobile data buffer 215 is between the first andsecond threshold values, then the data rate is not required to becompensated. Accordingly, in this case, the burst period is notadjusted. Furthermore, when an overflow occurs, the burst period isreduced (or shortened) so that a larger number of mobile service datapackets can be outputted from the mobile data buffer 215 than theaverage output rate. Conversely, when an underflow occurs, the burstperiod is extended so that a smaller number of mobile service datapackets can be outputted from the mobile data buffer 215 than theaverage output rate.

At this point, according to the second embodiment of the presentinvention, the buffer controller 217 sets the first and second thresholdvalues and adjusts the burst period. More specifically, the buffercontroller 217 monitors the mobile data buffer 215. Then, when anoverflow or underflow occurs, the buffer controller 217 adjusts theburst period among the transmission parameters of the signalinginformation provider 218. Subsequently, the signaling informationprovider 218 transmits the transmission parameters including theadjusted burst period information to the corresponding block.

FIG. 11 illustrates a flow chart showing an example of a method forcompensating data rate performed by the transmitter according to thesecond embodiment of the present invention. Herein, FIG. 11 illustratesan example wherein the data rate is compensated by adjusting the burstperiod. More specifically, the mobile service data packet demultiplexedby the demultiplexer 211 is temporarily stored in the mobile data buffer215 and then outputted (S601). At this point, the buffer controller 217determines whether the amount of data accumulated in the mobile databuffer 215 is larger than the first threshold value (S602).

When, the buffer controller 217 determines that the amount of dataaccumulated in the mobile data buffer 215 is larger than the firstthreshold value, the buffer controller 217 reduces the burst period sothat a larger number of mobile service data packets can be outputtedfrom the mobile data buffer 215 than the average output rate (S603).More specifically, while monitoring the amount of data being accumulatedin the mobile data buffer 215, when the number of data packets beingaccumulated in the mobile data buffer 215 is larger than thepredetermined first threshold value, the buffer controller 217temporarily controls the corresponding transmission parameter so thatthe burst period can be reduced. For example, when the current burstperiod is set to be equal to 60 fields, and when an overflow occurs, thecorresponding transmission parameter of the signaling informationprovider 218 is controlled so that the next burst period can be reducedto 59 fields, as shown in FIG. 10. In this case, the burst cycle is notaltered. Therefore, the burst-on section within the corresponding burstsection includes 18 fields, whereas the burst-off section includes 11fields. Thereafter, the adjusted transmission parameter is provided tothe pre-processor 216 and packet multiplexer 219 of the transmitter 200and simultaneously transmitted to the receiving system.

Meanwhile, the buffer controller 217 also determines whether the amountof data accumulated in the mobile data buffer 215 is smaller than thesecond threshold value (S605). When, the buffer controller 217determines that the amount of data accumulated in the mobile data buffer215 is smaller than the second threshold value, the buffer controller217 extends the burst period so that a smaller number of mobile servicedata packets can be outputted from the mobile data buffer 215 than theaverage output rate (S606).

More specifically, while monitoring the amount of data being accumulatedin the mobile data buffer 215, when the number of data packets beingaccumulated in the mobile data buffer 215 is smaller than thepredetermined second threshold value, the buffer controller 217temporarily controls the corresponding transmission parameter so thatthe burst period can be extended. For example, when the current burstperiod is set to be equal to 60 fields, and when an underflow occurs,the corresponding transmission parameter of the signaling informationprovider 218 is controlled so that the next burst period can be extendedto 61 fields. In this case, the burst cycle is not altered. Therefore,the burst-on section within the corresponding burst section includes 18fields, whereas the burst-off section includes 13 fields.

Thereafter, the adjusted transmission parameter is provided to thepre-processor 216 and packet multiplexer 219 of the transmitter 200 andsimultaneously transmitted to the receiving system. The pre-processor216 then performs pre-processes on the mobile service data packets basedupon the corresponding transmission parameter, and the packetmultiplexer 219 refers to the adjusted burst period so as to multiplexthe output of the packet jitter mitigator 214 and the output of thepre-processor 216, thereby transmitting the multiplexed data in a burststructure (S604).

FIG. 12 illustrates a flow chart showing an example of a method forcompensating data rate performed by the transmitter according to a thirdembodiment of the present invention. Herein, FIG. 12 illustrates anexample wherein the data rate is compensated by inserting or adding nulldata. According to the third embodiment of the present invention, inorder to differentiate the inserted or added null data from the nulldata packet for filler (or space-filler null data packet), which isinserted from the service multiplexer 100 in order to match the datarate, the null data inserted or added to compensate the data rate willbe referred to as a null data packet for transmission (or transmissionnull data packet). Although the space-filler null data packet is removed(or deleted) by the transmitter 200 without being processed, thetransmission null data packet inserted from the transmitter 200 isrecognizes as a mobile service data packet and processed accordingly,thereby transmitted to the receiving system.

Additionally, when the mobile service data being inputted to the mobileservice multiplexer 150 of the service multiplexer 100 is configured ina packet format, a null data packet may be required to be inserted inorder to match the amount of data during the compression encodingprocess. At this point, the inserted null data packet may be treated andprocessed identically as the mobile service data packets by the servicemultiplexer 100 and the transmitter 200. Thereafter, the processed nulldata packet is transmitted to the receiving system. Therefore, in thepresent invention, the null data packet inserted during the compressionencoding process will also be referred to as the transmission null datapacket. The A/V decoder of the receiving system removes the transmissionnull data packet from the inputted data and performs decoding only onthe mobile service data packet. At this point, in this embodiment of thepresent invention the insertion of the transmission null data packet isperformed at the input end of the pre-processor 216, and the removal ofthe transmission null data packet is performed at the input end of themobile data buffer 215.

The method of inserting the transmission null data packet to thepre-processor 216 is a method that may be applied when the transmissiondata rate of the transmitter 200 is larger than the output data rate ofthe service multiplexer 100, which corresponds to an underflow. In thiscase, the pre-processor 216 not only receives the mobile service datapacket outputted from the mobile data buffer 215 but also additionallyreceives the transmission null data packet. Conversely, the method ofremoving the transmission null data packet inputted to the pre-processor216 is a method that may be applied when the output data rate of theservice multiplexer 100 is larger than the transmission data rate of thetransmitter 200, which corresponds to an overflow. In this case, thetransmission null data packets included in the mobile service datapackets being inputted to the mobile data buffer 215 are removed,thereby matching the input and output data rates of the mobile databuffer 215.

According to the third embodiment of the present invention, first andsecond threshold values are also predetermined. And, when the amount ofdata accumulated in the mobile data buffer 215 is larger than the firstthreshold value, it is determined that an overflow has occurred. On theother hand, when the amount of data accumulated in the mobile databuffer 215 is smaller than the second threshold value, it is determinedthat an underflow has occurred. In this embodiment, the buffercontroller 217 determines (or sets) the first and second thresholdvalues. Accordingly, when an underflow occurs, a transmission null datapacket is generated and outputted to the pre-processor 216. On the otherhand, when an underflow occurs, a transmission null data packet inputtedto the mobile data buffer 215 is removed.

More specifically, the mobile service data packet demultiplexed by thedemultiplexer 211 is temporarily stored in the mobile data buffer 215and then outputted (S701). At this point, the buffer controller 217determines whether the amount of data accumulated in the mobile databuffer 215 is larger than the first threshold value (S702). When, thebuffer controller 217 determines that the amount of data accumulated inthe mobile data buffer 215 is larger than the first threshold value, andafter the transmission null data packet is removed from the data packetsinputted to the mobile data buffer 215, the remaining data packets areinputted to the mobile data buffer 215 (S703). More specifically, whenthe input data rate of the mobile data buffer 215 is larger than theoutput data rate of the mobile data buffer 215, thereby causing thenumber of data packets being accumulated in the mobile data buffer 215to become larger than the predetermined first threshold value, anoverflow occurs. Therefore, the null data packets for transmission (ortransmission null data packets) are partially removed from the mobileservice data packets inputted to the mobile data buffer 215, therebyadjusting the input and output data rates of the mobile data buffer 215.

Furthermore, the buffer controller 217 determines whether the amount ofdata accumulated in the mobile data buffer 215 is smaller than thesecond threshold value (S705). When, the buffer controller 217determines that the amount of data accumulated in the mobile data buffer215 is smaller than the second threshold value, the data packetsoutputted from the data packets are outputted to the pre-processor 216and, simultaneously, a transmission null data packet is generated andoutputted to the pre-processor 216 (S706). Accordingly, the data rateoutputted from the mobile data buffer 215 becomes lower in accordancewith the data rate being inputted to the mobile data buffer 215.Additionally, the pre-processor 216 recognizes the transmission nulldata packet inserted in Step 706 as a mobile service data packet andprocesses the transmission null data packet accordingly. Thereafter, theprocessed transmission null data packet is transmitted to the receivingsystem.

The A/V decoder of the receiving system removes the transmission nulldata packet from the inputted data and performs decoding only on themobile service data packet. The pre-processor 216 then performspre-processes on the mobile service data packets based upon thecorresponding transmission parameter, which is provided from thesignaling information provider 218, as described above. Then, the packetmultiplexer 219 refers to the burst size information and burst periodinformation within the transmission parameter, so as to multiplex theoutput of the packet jitter mitigator 214 and the output of thepre-processor 216. Thereafter, the multiplexed data are transmitted in aburst structure (S704).

According to the embodiment of the present invention, a portion of themobile service data packet or data group may be allocated for thesignaling information including the transmission parameters, wherein thetransmission parameters may be inserted. In this case, the signalinginformation is treated and processed identically as the mobile servicedata. Alternatively, the signaling information may be multiplexed withanother data type and then inserted. For example, when multiplexing theknown data and the mobile service data, the signaling information may beinserted in a place (or position) where known data may be insertedinstead of the actual known data. Otherwise, the signaling informationmay be combined with the known data and then inserted. Also, a portionof the reserved region within the field synchronization segment of thetransmission frame may be allocated for the signaling information,wherein the signaling information may be inserted.

Meanwhile, when the signaling information is inserted in the fieldsynchronization segment region or the known data region and thentransmitted, and when the signaling information passes through thetransmission channel, the reliability of the signaling information maybe reduced. Therefore, one of pre-defined patterns may be inserted basedupon the signaling information. At this point, the receiving systemperforms a correlation operation between the received signal and thepre-defined patterns so as to recognize the signaling information.

As described above, the description of the present invention presents amethod of temporarily adjusting the data rate by having the transmitter200 temporarily adjust the burst size or the burst period or by havingthe transmitter 200 remove or insert null data, when the output datarate of the service multiplexer 100 does not coincide with (or match)the transmission data rate of the transmitter 200. According to anotherembodiment of the present invention, at least one of the methods oftemporarily adjusting the burst size, temporarily adjusting the burstperiod, and removing or inserting null data may be used independently orin combination in order to adjust the data rate. For example, when anoverflow occurs, the burst period is adjusted. Alternatively, when anunderflow occurs, the null data may be inserted.

FIG. 13 illustrates a block diagram showing a structure of a receivingsystem according to the present invention. Herein, data inputted to thereceiving system of FIG. 13 may include the transmission null data,which have been inserted by the transmitting system so as to adjust thedata rate. Also, burst period information and burst size informationincluded in the transmission parameter received by the receiving systemmay be variable instead of being fixed. Furthermore, the receivingsystem according to the present invention uses known data information,which is inserted in the mobile service data section and, then,transmitted by the transmitting system, so as to perform carrierrecovery, timing recovery, frame synchronization recovery, and channelequalization, thereby enhancing the receiving performance.

Referring to FIG. 13, the receiving system includes a demodulator 801,an equalizer 802, a known data detector (or known sequence detector)803, a signaling information processor 804, a block decoder 805, a datadeformatter 806, a RS frame decoder 807, and a mobile service dataderandomizer 808. Herein, a null data remover 809, which removes thetransmission null data inserted by the transmitting system, may befurther included at the output end of the mobile service dataderandomizer 808. Furthermore, the receiving system also includes a datadeinterleaver 810, a RS decoder 811, and a main service dataderandomizer 812.

More specifically, a frequency of a particular channel received througha tuner (not shown) is down-converted to an intermediate frequency (IF)signal. Then, the tuner outputs the down-converted IF signal to thedemodulator 801 and the known sequence detector 803. The demodulator 801performs self gain control, carrier recovery, and timing recoveryprocesses on the inputted IF signal, thereby modifying the IF signal toa baseband signal. Then, the demodulator 801 outputs the modified signalto the equalizer 802 and the known sequence detector 803. The equalizer802 compensates the distortion of the channel included in thedemodulated signal and then outputs the error-compensated signal to theblock decoder 805.

At this point, the known sequence detector 803 detects the knownsequence place inserted by the transmitting end from the input/outputdata of the demodulator 801 (i.e., the data prior to the demodulationprocess or the data after the demodulation process). Thereafter, theplace information (or position indicator) along with the symbol sequenceof the known data, which are generated from the detected place, isoutputted to the demodulator 801 and the equalizer 802. Also, the knownsequence detector 803 outputs a set of information to the block decoder805. This set of information is used to allow the block decoder 805 ofthe receiving system to identify the mobile service data that areprocessed with additional encoding from the transmitting system and themain service data that are not processed with additional encoding.

In addition, although the connection status is not shown in FIG. 13, theinformation detected from the known sequence detector 803 may be usedthroughout the entire receiving system and may also be used in the datadeformatter 806 and the RS frame decoder 807. The demodulator 801 usesthe known data (or sequence) position indicator and the known datasymbol sequence during the timing and/or carrier recovery, therebyenhancing the demodulating performance. Similarly, the equalizer 802uses the known sequence position indicator and the known data symbolsequence so as to enhance the equalizing performance. Moreover, thedecoding result of the block decoder 805 may be fed-back to theequalizer 802, thereby enhancing the equalizing performance.

Meanwhile, if the data being inputted to the block decoder 805 afterbeing channel equalized from the equalizer 802 correspond to the mobileservice data having additional encoding and trellis encoding performedthereon by the transmitting system, trellis decoding and additionaldecoding processes are performed on the inputted data as inverseprocesses of the transmitting system. Alternatively, if the data beinginputted to the block decoder 805 correspond to the main service datahaving only trellis encoding performed thereon, and not the additionalencoding, only the trellis decoding process is performed on the inputteddata as the inverse process of the transmitting system. The data groupdecoded by the block decoder 805 is inputted to the data deformatter806, and the main service data packet is inputted to the datadeinterleaver 810.

More specifically, if the inputted data correspond to the main servicedata, the block decoder 805 performs Viterbi decoding on the inputteddata so as to output a hard decision value or to perform a hard-decisionon a soft decision value, thereby outputting the result. Meanwhile, ifthe inputted data correspond to the mobile service data, the blockdecoder 805 outputs a hard decision value or a soft decision value withrespect to the inputted mobile service data. In other words, if theinputted data correspond to the mobile service data, the block decoder805 performs a decoding process on the data encoded by the blockprocessor and trellis encoding module of the transmitting system.

At this point, the RS frame encoder of the pre-processor included in thetransmitting system may be viewed as an external code. And, the blockprocessor and the trellis encoder may be viewed as an internal code. Inorder to maximize the performance of the external code when decodingsuch concatenated codes, the decoder of the internal code should outputa soft decision value. Therefore, the block decoder 805 may output ahard decision value on the mobile service data. However, when required,it may be more preferable for the block decoder 805 to output a softdecision value.

Meanwhile, the data deinterleaver 810, the RS decoder 811, and the mainservice data derandomizer 812 are blocks required for receiving the mainservice data. Therefore, the above-mentioned blocks may not be requiredin the structure of a receiving system that only receives the mobileservice data. The data deinterleaver 810 performs an inverse process ofthe data interleaver included in the transmitting system. In otherwords, the data deinterleaver 810 deinterleaves the main service dataoutputted from the block decoder 805 and outputs the deinterleaved mainservice data to the RS decoder 811. The RS decoder 811 performs asystematic RS decoding process on the deinterleaved data and outputs theprocessed data to the main service data derandomizer 812. The mainservice data derandomizer 812 receives the output of the RS decoder 811and generates a pseudo random data byte identical to that of therandomizer included in the transmitting system. Thereafter, the mainservice data derandomizer 812 performs a bitwise exclusive OR (XOR)operation on the generated pseudo random data byte, thereby insertingthe MPEG synchronization bytes to the beginning of each packet so as tooutput the data in 188-byte main service data packet units.

Meanwhile, the data being outputted from the block decoder 805 to thedata deformatter 806 are inputted in the form of a data group. The datadeformatter 806 removes the known data, trellis initialization data, andMPEG header that were inserted in the main service data and data group.The data deformatter 806 also removes the RS parity that was added bythe RS encoder/non-systematic RS encoder or the non-systematic RSencoder of the transmitting system. Thereafter, the processed data areoutputted to the RS frame decoder 807. More specifically, the RS framedecoder 807 receives only the RS encoded and/or CRC encoded mobileservice data that are transmitted from the data deformatter 806.

Meanwhile, since the signaling information processor 804 may know theconfiguration of the inputted data group, the signaling informationprocessor 804 extracts transmission parameters, which includes burstsize information and burst period information, from the signalinginformation included in the data group that is outputted from theequalizer 802 or the block decoder 803. Thereafter, the signalinginformation processor 804 provides the extracted transmission parameterto the corresponding block requiring the particular transmissionparameter. When the power is turned on only during the burst section soas to receive the mobile service, information such as the burst sizeinformation and the burst period information within the transmissionparameters are also provided to a block controlling power supply (notshown).

The RS frame decoder 807 performs an inverse process of the RS frameencoder included in the transmitting system so as to correct the errorwithin the RS frame. Then, the RS frame decoder 807 adds the 1-byte MPEGsynchronization service data packet, which had been removed during theRS frame encoding process, to the error-corrected mobile service datapacket. Thereafter, the processed data packet is outputted to the mobileservice data derandomizer B08. The mobile service data derandomizer 808performs a derandomizing process, which corresponds to the inverseprocess of the randomizer included in the transmitting system, on thereceived mobile service data. Thereafter, the derandomized data areoutputted, thereby obtaining the mobile service data transmitted fromthe transmitting system. At this point, if the transmission null datainserted by the transmitting system exist within the received data, thenull data remover 809 removes (or discards) the transmission null data,so that only the mobile service data can be outputted. The null dataremover 809 may also be included in the A/V decoder, which recovers thecompression encoded mobile service data to the initial state prior tobeing processed with compression encoding.

As described above, the digital broadcasting system and method ofprocessing data according to the present invention have the followingadvantages. More specifically, the digital broadcasting system and dataprocessing method according to the present invention is robust against(or resistant to) any error that may occur when transmitting mobileservice data through a channel. And, the present invention is alsohighly compatible to the conventional system. Moreover, the presentinvention may also receive the mobile service data without any erroreven in channels having severe ghost effect and noise.

Additionally, by performing error correction encoding and errordetection encoding processes on the mobile service data and transmittingthe processed data, the present invention may provide robustness to themobile service data, thereby enabling the data to effectively respond tothe frequent change in channels. Also, when the present inventionmultiplexes the main service data and the mobile service data in a burststructure, a relative position of a main service data packet isre-adjusted and then multiplexed, thereby mitigating packet jitter,which may occur when the receiving system receives the multiplexed mainservice data packet.

Moreover, when a difference occurs between an output data rate of aservice multiplexer and a transmission data rate of a transmitter, thetransmitter of the present invention temporarily adjusts thetransmission parameters so as to match (or put in accord) the datarates, thereby facilitating the adjustment of the data rates.Furthermore, the present invention is even more effective when appliedto mobile and portable receivers, which are also liable to a frequentchange in channel and which require protection (or resistance) againstintense noise.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A digital television (DTV) transmitter forprocessing digital broadcast data, the DTV transmitter comprising: asignal generator for generating a data group having first, second, andthird regions, the first region and the third region having mobile dataand main data place holders, the second region having mobile data, knowndata sequences, trellis initialization data, MPEG header place holders,RS parity data place holders, and transmission parameter data; ade-interleaver for de-interleaving the data group; a packet formatterfor removing the RS parity data place holders and the main data placeholders from the de-interleaved data group and replacing the MPEG headerplace holders in the de-interleaved data group with MPEG headers,thereby outputting mobile data packets which include the mobile data,the known data sequences, the trellis initialization data, the MPEGheaders, and the transmission parameter data; a packet jitter mitigatorfor adjusting packet timing and a program clock reference (PCR) of maindata packets including main data; a multiplexer for multiplexing themobile data packets with the main data packets; an RS encoder for addingRS parity data to the multiplexed mobile and main data packets; and aninterleaver for interleaving the multiplexed mobile and main datapackets including the RS parity data.
 2. The DTV transmitter of claim 1,wherein the interleaver is a convolutional data byte interleaver.
 3. TheDTV transmitter of claim 1, further comprising: a trellis encoder fortrellis-encoding the interleaved mobile and main data packets, whereinthe trellis encoder is initialized at a start of each of the known datasequences.
 4. A method of processing digital broadcast data in a digitaltelevision (DTV) transmitter, the method comprising: generating a datagroup having first, second, and third regions, the first region and thethird region having mobile data and main data place holders, the secondregion having mobile data, known data sequences, trellis initializationdata, MPEG header place holders, RS parity data place holders, andtransmission parameter data; de-interleaving the data group; removingthe RS parity data place holders and the main data place holders fromthe de-interleaved data group and replacing the MPEG header placeholders in the de-interleaved data group with MPEG headers, therebyoutputting mobile data packets which include the mobile data, the knowndata sequences, the trellis initialization data, the MPEG headers, andthe transmission parameter data; adjusting packet timing and a programclock reference (PCR) of main data packets including main data;multiplexing in a multiplexer the mobile data packets with the main datapackets; and interleaving the multiplexed mobile and main data packetsincluding the RS parity data.
 5. The method of claim 4, whereininterleaving the multiplexed mobile and main data packets comprisesinterleaving the multiplexed mobile and main data packets by aconvolutional data byte interleaver.
 6. The method of claim 4, furthercomprising: trellis-encoding, by a trellis encoder, the interleavedmobile and main data packets, wherein the trellis encoder is initializedat a start of each of the known data sequences.